Wireless communications systems, for example packet data communications systems, may utilize shared channels wherein the network allocates resources to a mobile station for uplink transmissions based on the number of mobiles requesting resources, the channel conditions of the mobile station, and the services for which the mobile station is requesting resources.
The mobile station will transmit information to the network regarding a buffer status of each radio bearer or for a group of radio bearers. Typically each service utilized by the mobile station is mapped to one radio bearer. Each service and thus, each radio bearer, is associated with a priority. In order to minimize the amount of signaling overhead, it is preferred to have a mobile station indicate the amount of data in its buffer across all radio bearers and indicate for example, the highest priority radio bearer that has data waiting to be sent. This allows the network to assign resources with some degree of fairness.
However, since the network does not have the absolute latest information regarding each and every radio bearer it typically will assign resources to a mobile station that may be used to transmit data from a number of radio bearers. One issue with such a mechanism is that the network is not in control of the exact usage of resources by the mobile station.
For example, the mobile station may have data in the buffer for radio bearer (RB) #1, 2, 3 and 4, wherein the sequence number also indicates a priority of the data. For example, RB #4 may indicate the lowest priority data while RB#1 may indicate the highest priority data.
However, if another mobile station has data buffered that is in a higher priority queue, the network should not allow a mobile station to send data from RB#4 because of its very low data priority. Instead it would be preferable for the network to allocate resources to the mobile station with the highest priority data.
On the other hand, preventing mobile stations from transmitting low priority data when high priority data is buffered by other mobile stations may result in a “starvation” effect wherein the low priority data may be queued indefinitely or otherwise for an inordinate amount of time.
The 3rd Generation Partnership Project Technical Standard, 3GPP TS 25.309, describes procedures adopted for a shared uplink channel, Enhanced Dedicated Channel (E-DCH) for UMTS networks. Per the standard, a mobile station may send the identity of the highest priority logical channel with data in buffer and the total amount of data in its buffer across all the radio bearers. Because the uplink is designed as a synchronous Hybrid Automatic Repeat Request (HARQ) channel, the mobile station may then choose data from all of its radio bearers as long as it does not exceed the resources assigned.
In the enhanced uplink the mobile sends a “happy bit” when the time required to transmit data in radio bearers mapped to scheduled transmissions, as opposed to non-scheduled transmissions, exceeds a Happy bit delay condition. This procedure is applied for all radio bearers utilizing scheduled grants. Unfortunately, there is no ability to discriminate between radio bearers with different priorities.
Thus, there is a need for apparatuses and methods for restricting a mobile station usage of resource grants for transmission of data while avoiding starvation of low priority data.